Inert soil-mounting wall protecting agent and preparation method thereof

Abstract

The invention provides an inert soil protecting agent and a preparation method thereof, the inert soil protecting agent comprises a liquid A and a liquid B, and the weight ratio of the liquid A to the liquid B is 3: 1-10: 1; wherein the liquid A comprises bentonite, a modification additive and water, the bentonite accounts for 20%-40% of the total weight of the liquid A, the modification additive accounts for 5%-15% of the total weight of the liquid A, and the water accounts for 50%-70% of the total weight of the liquid A; and the liquid B is water glass. By means of the method, the problems that in shield tunnel construction, a shield body is prone to being locked due to soil body sedimentation, and a pipe is prone to being blocked can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel construction, and more specifically to an inert soil retaining wall agent and a preparation method thereof. Background Art

[0002] In urban rail transit construction, the shield method has gradually become the preferred construction technology due to its reduced environmental impact, convenient settlement control, construction safety and efficient construction progress. Long-term engineering practice and research have revealed that since the diameter of the shield cutter is slightly larger than the diameter of the shield shell, there is a gap of about 3 cm between the shield shell and the newly excavated soil layer during the shield excavation process. When the soil conditions are poor or the ground settlement needs to be strictly controlled, the gap between the shield shell and the newly excavated soil layer needs special treatment. During the shield excavation process, the clay soil is converted into fine soil particles after being cut by the cutter disc, and the so-called "mud cake" is formed in the central area of ​​the cutter disc. As these mud cakes increase, the cutting efficiency of the cutter disc gradually decreases.

[0003] In the case of serious accumulation of mud cakes, the traditional approach is to manually clean the mud cakes by putting them into the bunker under pressure. This approach is not only time-consuming and labor-intensive, but also involves extremely high construction risks and economic losses. In strata with sufficient moisture, mud cakes in the bunker during shield excavation can easily trigger gushing, causing large fluctuations in the internal pressure of the bunker, which in turn can cause surface subsidence or even landslides. In addition, the presence of mud cakes can also lead to a rapid increase in the bunker temperature, an increase in the thrust of the shield, severe wear of the cutter, and a reduction in the sealing performance of the main drive. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide an inert soil wall protection agent and a preparation method thereof to solve the problems of soil settlement, easy locking of the shield body and easy blockage of the pipe during shield tunnel construction.

[0005] The present invention provides an inert soil wall protection agent, comprising: liquid A and liquid B, wherein the weight ratio of the liquid A to the liquid B is 3:1 to 10:1; wherein:

[0006] The liquid A comprises: bentonite, a modifying additive and water, wherein the bentonite accounts for 20-40% of the total weight of the liquid A, the modifying additive accounts for 5-15% of the total weight of the liquid A, and the water accounts for 50-70% of the total weight of the liquid A;

[0007] The B liquid is water glass.

[0008] Preferably, the bentonite is calcium-based bentonite, wherein:

[0009] The bentonite has a 200-mesh particle size passing rate of more than 97%, a moisture content of less than 10%, and a water absorption rate of more than 200%.

[0010] Preferably, the modified additives include one or more of gum powder, soluble salts, cellulose and polymers.

[0011] Preferably, the gum powder is gum arabic powder, wherein:

[0012] At a temperature of 25°C, the viscosity of the gum powder is 80-120 CPS;

[0013] The pH value of the gum powder is 4.1-4.6, and the gum powder accounts for 0-3% of the total weight of the A liquid.

[0014] Preferably, the soluble salt is one or more of sodium chloride, calcium chloride and magnesium chloride, and the soluble salt accounts for 0-4% of the total weight of the liquid A.

[0015] Preferably, the cellulose is one or more of sodium carboxymethyl cellulose, microcrystalline cellulose, bacterial cellulose, hydroxypropyl cellulose, and nanocellulose, and the cellulose accounts for 0-4% of the total weight of the A liquid.

[0016] Preferably, the polymer is one or more of polyacrylamide, polyacrylamide, polyvinyl alcohol, and sodium polyacrylate, and the polymer accounts for 0-4% of the total weight of the A liquid.

[0017] Preferably, the B liquid has a Baume degree of 38°Bé and a modulus of 3.1.

[0018] The present invention also provides a method for preparing an inert soil wall protecting agent, which is used to prepare the above-mentioned inert soil wall protecting agent. The preparation method comprises:

[0019] According to the preset ratio, the bentonite and the modifying additives in the liquid A are mixed evenly to form a powder;

[0020] Adding water to the powder and mixing and stirring to form a fluid solution;

[0021] Liquid B is added to the fluid solution and stirred to form a paste-like inert soil wall protective agent.

[0022] Preferably, the chemical equation between the A liquid and the B liquid is:

[0023] NaCl(aq)+CaCl2(aq)=NaCl(aq)+CaCl2(aq)

[0024] NaCl(aq)+Na2Si03(aq)=NaCl(aq)+Na2Si03(aq)+2NaCl(s)

[0025] CaCl2(aq)+Na2Si03(aq)→CaSi03(s)+2NaCl(aq)

[0026] Na2Si03+CaCl2+H20→CaSi03·nH20+2NaCl.

[0027] Preferably, the time for the chemical reaction between the liquid A and the liquid B is 5s to 20s.

[0028] Preferably, the cross-plate shear strength of the inert soil wall protection agent is not less than 1.1 kPa, the water retention rate is not less than 85%, and the viscosity ranges from 300 dpa.s to 600 dpa.s.

[0029] It can be seen from the above technical scheme that the inert soil wall protection agent and the preparation method thereof provided by the present invention can achieve the following beneficial effects compared with the prior art:

[0030] (1) Liquid A and Liquid B are blended physically and chemically, wherein the physical effect of the powder is that water molecules enter the interlayer gap of bentonite, causing the interlayer spacing to increase and expand, thereby adsorbing and modifying the additives to react. In addition, the reaction generated during the powder blending can promote rapid gelation between the components.

[0031] (2) The material types and ratios of liquid A and liquid B have been carefully set to balance multiple properties. They all perform well in terms of anti-subsidence, pumpability and water retention. Among them, they have good pumpability and anti-subsidence properties, which can not only avoid the risk of pipe blockage, but also ensure the effective filling of formation voids. The cross-plate shear strength is not less than 1.1kPa, indicating that it has a certain degree of anti-subsidence. The water retention rate is not less than 85%, and the viscosity range is between 300dpa.s and 600dpa.s, indicating that the slurry loss is less, thereby avoiding the risk of groundwater scouring, and can remain stable for a long time to ensure the filling effect.

[0032] (3) After the mixture of liquid A and liquid B, the reaction time can be completed within 5s to 20s. This method can not only quickly and effectively fill the gap between the shield machine and the soil caused by over-excavation of the cutter head, effectively inhibit the settlement and structural deformation of the soil in the underpass project, but also the generated paste has good lubricity, which is conducive to the construction of the shield machine.

[0033] (4) The inert soil wall protection agent prepared by the present invention has a wide range of applicability, and can be used not only to control soil settlement and deformation, but also to repair the shutdown of shield machines, prevent subsidence, and improve hollow strata. In addition, the purpose of mixed grouting and filling gaps can be achieved by only using the grouting holes on the shield shell of the shield machine in combination with the double-liquid grouting equipment.

[0034] (5) The inert soil wall protection agent prepared by the present invention has strong cohesive force. Once injected, it can effectively fill the stratum voids and bear the load. It also has strong anti-penetration ability and can effectively prevent groundwater from invading the interior of the shield machine.

[0035] (6) The inert soil wall protection agent prepared by the present invention has excellent anti-dilution ability, has no adverse reaction to groundwater, has strong adaptability, and is not easily dispersed by groundwater after injection.

[0036] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easy to understand. In the accompanying drawings:

[0038] Figure 1 This is a powder diagram of the inert soil wall protection agent according to Example 4 of the present invention;

[0039] Figure 2 This is a diagram of a fluidity solution formed by mixing powder and water according to Example 4 of the present invention;

[0040] Figure 3 This is a paste image of the inert soil wall protecting agent according to Example 4 of the present invention;

[0041] Figure 4 The present invention is a flow chart of a method for preparing an inert soil wall protection agent according to an embodiment of the present invention.

[0042] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0043] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0044] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In view of the aforementioned problems of soil settlement, easy blocking of shield body and easy pipe blocking in shield tunnel construction, the present invention provides an inert soil wall protection agent and a preparation method thereof. The present invention balances multiple properties by carefully setting the material types and ratios of liquid A and liquid B. It performs well in terms of anti-subsidence, pumpability and water retention. Among them, it has good pumpability and anti-subsidence, which can not only avoid the risk of pipe blocking, but also ensure the effective filling of stratum voids. Good water retention can avoid the risk of groundwater scouring, and can remain stable for a long time to ensure the filling effect. The inert soil wall protection agent can not only quickly and effectively fill the gap between the shield machine and the soil body caused by over-excavation of the cutter head, but also effectively suppress the settlement and structural deformation of the soil body in the underpass project. At the same time, the generated paste has good lubricity, which is conducive to the construction of the shield machine. In addition, the inert soil wall protection agent can not only be used to control soil settlement and deformation, but also can be used for various working conditions such as shutdown repair of shield machines, prevention of subsidence and improvement of hollow strata.

[0046] The invention provides an inert soil wall-protecting agent, comprising: liquid A and liquid B, wherein the weight ratio of the liquid A to the liquid B is 3:1-10:1; wherein the liquid A comprises: bentonite, a modifying additive and water, wherein the bentonite accounts for 20-40% of the total weight of the liquid A, the modifying additive accounts for 5-15% of the total weight of the liquid A, and the water accounts for 50-70% of the total weight of the liquid A; and the liquid B is water glass.

[0047] The bentonite is calcium-based bentonite, wherein the 200-mesh particle size pass rate of the bentonite is greater than 97%, the moisture content is less than 10%, and the water absorption rate is greater than 200%.

[0048] The modified additives include one or more of gum powder, soluble salt, cellulose and polymer. The gum powder is gum arabic powder, and the viscosity of the gum powder is 80-120 CPS at a temperature of 25° C. The pH value of the gum powder is 4.1-4.6, and the gum powder accounts for 0-3% of the total weight of the A liquid.

[0049] Wherein, the soluble salt is one or more of sodium chloride, calcium chloride and magnesium chloride, and the soluble salt accounts for 0-4% of the total weight of the A liquid.

[0050] Wherein, the cellulose is one or more of sodium carboxymethyl cellulose, microcrystalline cellulose, bacterial cellulose, hydroxypropyl cellulose, and nanocellulose, and the cellulose accounts for 0-4% of the total weight of the A liquid.

[0051] Wherein, the polymer is one or more of polyacrylamide, polyacrylamide, polyvinyl alcohol, and sodium polyacrylate, and the polymer accounts for 0-4% of the total weight of the A liquid.

[0052] The B liquid has a Baume degree of 38°Bé and a modulus of 3.1.

[0053] Figure 4 The preparation method of the inert soil wall protection agent according to an embodiment of the present invention is shown. Figure 4 As shown, the present invention provides a method for preparing an inert soil wall protecting agent, which is used for the above-mentioned inert soil wall protecting agent, and the preparation method comprises the following steps:

[0054] S1: According to a preset ratio, the bentonite and the modifying additives in the liquid A are mixed evenly to form a powder;

[0055] S2: adding water to the powder and mixing and stirring to form a fluid solution;

[0056] S3: Add liquid B to the fluid solution and stir to form a paste-like inert soil wall protective agent.

[0057] In the preparation process from step S1 to step S3, liquid A and liquid B are blended physically and chemically, wherein the physical action of the powder is that water molecules enter the interlayer gap of bentonite, causing the interlayer gap to increase and expand, thereby adsorbing the modified additive to react. The chemical equation between the powders includes:

[0058] NaCl(aq)+CaCl2(aq)=NaCl(aq)+CaCl2(aq)

[0059] NaCl(aq)+Na2Si03(aq)=NaCl(aq)+Na2Si03(aq)+2NaCl(s)

[0060] CaCl2(aq)+Na2Si03(aq)→CaSi03(s)+2NaCl(aq)

[0061] Na2Si03+CaCl2+H20→CaSi03·nH20+2NaCl

[0062] Therefore, benefiting from the reaction generated during powder blending, rapid gelation between the components is promoted.

[0063] The time for the chemical reaction between the liquid A and the liquid B is 5s to 20s. This method can not only quickly and effectively fill the gap between the shield machine and the soil caused by over-excavation of the cutter head, but also effectively inhibit the settlement and structural deformation of the soil in the underpass project. At the same time, the generated paste has good lubricity, which is beneficial to the construction of the shield machine.

[0064] In the embodiments of the present invention, the prepared inert soil wall protection agent performs well in terms of anti-subsidence, pumpability and water retention. It has good pumpability and anti-subsidence, which not only avoids the risk of pipe blockage, but also ensures the effective filling of formation voids. The cross-plate shear strength is not less than 1.1 kPa, indicating that it has a certain anti-subsidence property. The water retention rate is not less than 85%, and the viscosity range is between 300 dpa.s and 600 dpa.s, indicating that the slurry loss is less, avoiding the risk of groundwater scouring, and can remain stable for a long time, ensuring the filling effect.

[0065] The inert soil wall protection agent prepared by the present invention has a wide range of applicability, and can be used not only to control soil settlement and deformation, but also to repair the shutdown of shield machines, prevent subsidence, and improve hollow strata, etc. Moreover, the purpose of mixed grouting and filling gaps can be achieved by only using the grouting holes on the shield shell of the shield machine in combination with the double-liquid grouting equipment.

[0066] The present invention is further described in detail below in conjunction with the embodiments and drawings. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0067] Example 1

[0068] In liquid A, bentonite accounts for 40%, modified additives account for 10%, of which gum powder accounts for 2%, soluble salt accounts for 2%, cellulose accounts for 3%, polymer accounts for 3%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 4:1.

[0069] Example 2

[0070] In liquid A, bentonite accounts for 35%, modified additives account for 5%, of which gum powder accounts for 1%, soluble salt accounts for 2%, cellulose accounts for 1%, polymer accounts for 1%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 5:1.

[0071] Example 3

[0072] In liquid A, bentonite accounts for 20%, modified additives account for 10%, of which gum powder accounts for 2%, soluble salt accounts for 2%, cellulose accounts for 3%, polymer accounts for 3%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 6:1.

[0073] Example 4

[0074] In liquid A, bentonite accounts for 40%, modified additives account for 5%, of which gum powder accounts for 1%, soluble salt accounts for 1%, cellulose accounts for 2%, polymer accounts for 1%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 4:1.

[0075] Example 5

[0076] In liquid A, bentonite accounts for 30%, modified additives account for 7%, of which gum powder accounts for 1%, soluble salt accounts for 2%, cellulose accounts for 2%, polymer accounts for 2%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 6:1.

[0077] Example 6

[0078] In liquid A, bentonite accounts for 30%, modified additives account for 10%, of which gum powder accounts for 2%, soluble salt accounts for 2%, cellulose accounts for 3%, polymer accounts for 3%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 5:1.

[0079] Example 7

[0080] In liquid A, bentonite accounts for 20%, modified additives account for 5%, of which gum powder accounts for 1%, soluble salt accounts for 2%, cellulose accounts for 1%, polymer accounts for 1%, and the rest is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 3:1.

[0081] Example 8

[0082] In liquid A, bentonite accounts for 30%, modified additives account for 8%, of which gum powder accounts for 2%, soluble salt accounts for 2%, cellulose accounts for 2%, polymer accounts for 2%, and the balance is water. Liquid B is water glass, and the weight ratio of liquid A to liquid B is 5:1.

[0083] Performance Testing

[0084] In terms of fluidity test, according to the cement paste fluidity test standard in the "Concrete Admixture Uniformity Test Method" (GB / T8074-2012), the fluidity of the inert soil wall protector sample was evaluated after mixing for 3 hours. The size of the truncated cone circular mold used is 40mm in diameter, 50mm in bottom diameter, and 50mm in height, and the inner wall of the mold is smooth and seamless. The repeatability of the test results is limited to 5mm, and the reproducibility limit is 10mm.

[0085] In terms of viscosity testing, according to the viscosity determination method of "Determination of Liquid Viscosity" (GB / T 22235-2008), the viscosity of the inert soil wall protection agent sample after mixing for 3 hours was evaluated using the NDJ-5S rotational viscometer. If double measurements are performed, it is necessary to verify whether the difference between the two measurement results is less than or equal to 10% of the average value, otherwise a third measurement is required.

[0086] In terms of the unconfined compressive strength test, the unconfined compressive strength test of the inert soil wall protection agent grouting body is carried out according to the specifications of "Highway Engineering Cement Mixing Piles Quality Inspection Procedure" (DB32 / T 2283-2012).

[0087] The test results are shown in Table 1:

[0088] Table 1 Comprehensive performance of inert soil wall protection agent

[0089] Example Fluidity(mm) Viscosity (Pas) Compressive strength(MPa) 1 5.1 47 0.071 2 6.3 35 0.063 3 6.8 30 0.055 4 4.3 55 0.14 5 4.9 40 0.068 6 5.6 42 0.068 7 5.1 47 0.072 8 6.7 31 0.052

[0090] According to the experimental data in the above table, it is analyzed that Examples 1-8 can successfully prepare gel pastes with anti-sinking effect, through comparison between viscosity, fluidity and compressive strength.

[0091] In the embodiment, viscosity and fluidity show a clear inverse relationship, that is, when fluidity decreases, viscosity increases. As bentonite further expands, water is gradually consumed, resulting in a high viscosity level that tends to stabilize regardless of the soil-water ratio. Under normal pressure conditions, its fluidity is almost completely lost.

[0092] Comparing the compressive strength in Examples 1-8, it can be seen that the strength of the inert soil wall protector is affected differently by the addition ratio of bentonite, modifying additives and water glass. However, after filling the gap, the inert soil wall protector can play a role in supporting the soil and controlling the deformation of the stratum in a relatively short period of time. Through comprehensive comparison, the composition ratio developed in Example 4 has the best anti-sinking ability and can effectively support the soil pressure.

[0093] In Example 4, bentonite is mixed with a modifying additive to form a powder such as Figure 1 As shown, the powder is mixed with water to form a flowing liquid such as Figure 2 As shown, the formed paste-like inert soil wall protection agent is as Figure 3 shown.

[0094] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An inert soil wall protection agent, characterized in that: include: Liquid A and liquid B, the weight ratio of liquid A to liquid B is 3:1 to 10:1; wherein, The liquid A comprises: bentonite, a modifying additive and water, wherein the bentonite accounts for 20-40% of the total weight of the liquid A, the modifying additive accounts for 5-15% of the total weight of the liquid A, and the water accounts for 50-70% of the total weight of the liquid A; The B liquid is water glass.

2. The inert soil wall protection agent according to claim 1, characterized in that: The bentonite is calcium-based bentonite, wherein: The bentonite has a 200-mesh particle size passing rate of more than 97%, a moisture content of less than 10%, and a water absorption rate of more than 200%.

3. The inert soil wall protection agent according to claim 1, characterized in that: The modified additives include one or more of gum powder, soluble salt, cellulose and polymer.

4. The inert soil wall protection agent according to claim 3, characterized in that: The gum powder is gum arabic powder, wherein At a temperature of 25°C, the viscosity of the gum powder is 80-120 CPS; The pH value of the gum powder is 4.1-4.6, and the gum powder accounts for 0-3% of the total weight of the A liquid.

5. The inert soil wall protection agent according to claim 3, characterized in that: The soluble salt is one or more of sodium chloride, calcium chloride and magnesium chloride, and the soluble salt accounts for 0-4% of the total weight of the A liquid.

6. The inert soil wall protection agent according to claim 3, characterized in that: The cellulose is one or more of sodium carboxymethyl cellulose, microcrystalline cellulose, bacterial cellulose, hydroxypropyl cellulose, and nanocellulose, and the cellulose accounts for 0-4% of the total weight of the A liquid.

7. The inert soil wall protection agent according to claim 3, characterized in that: The polymer is one or more of polyacrylamide, polyacrylamide, polyvinyl alcohol and sodium polyacrylate, and the polymer accounts for 0-4% of the total weight of the A liquid.

8. The inert soil wall protection agent according to claim 1, characterized in that: The B liquid has a Baume degree of 38°Bé and a modulus of 3.

1.

9. A method for preparing an inert soil wall protection agent, characterized in that: Used for preparing the inert soil wall protection agent according to any one of claims 1 to 8, the preparation method comprising: According to the preset ratio, the bentonite and the modifying additives in the liquid A are mixed evenly to form a powder; Adding water to the powder and mixing and stirring to form a fluid solution; Liquid B is added to the fluid solution and stirred to form a paste-like inert soil wall protective agent.

10. The method for preparing the inert soil wall protection agent according to claim 9, characterized in that: The chemical equation between the A liquid and the B liquid is: NaCl(aq)+CaCl2(aq)=NaCl(aq)+CaCl2(aq) NaCl(aq)+Na2Si03(aq)=NaCl(aq)+Na2Si03(aq)+2NaCl(s) CaCl2(aq)+Na2Si03(aq)→CaSi03(s)+2NaCl(aq) Na2Si03+CaCl2+H20→CaSi03·nH20+2NaCl.

11. The method for preparing the inert soil wall protection agent according to claim 10, characterized in that: The time for the chemical reaction between the liquid A and the liquid B is 5s to 20s.

12. The method for preparing the inert soil wall protection agent according to claim 9, characterized in that: The cross-plate shear strength of the inert soil wall-protecting agent is not less than 1.1 kPa, the water retention rate is not less than 85%, and the viscosity ranges from 300 dPa.s to 600 dPa.s.

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